ATOTONILCO DE TULA, Mexico, Jan 25, (AP): When Dayana Castro heard that the U.S. asylum appointment she waited over a year for was canceled in an instant, she had no doubt: She was heading north any way she could. The 25-year-old migrant, her husband and their 4- and 7-year-old children had nothing left at home in Venezuela.

They already had trekked the perilous Darien Gap jungle dividing Colombia and Panama and criminal groups that prey on migrants like them. Castro was one of tens of thousands of migrants across Mexico with appointments to apply for U.S. asylum at the border scheduled out through February until President Donald Trump took office and issued a series of executive orders to beef up border security and slash migration.

One ended the use of the CBP One app that had allowed nearly 1 million people, many seeking asylum, to legally enter the U.S. since January 2023. "We’re going to keep going. We can’t go home after all we’ve been through, after all the countries we’ve fought our way through, only to give up now,” she said from a small shelter in central Mexico beside a freight train line they were riding north.

Now, migrants like her are adjusting to a new and uncertain reality. Many remain determined to reach the US through more dangerous means, riding freight trains, hiring smugglers and dodging authorities. Some lined up in Mexico's refugee offices to seek asylum in that country, while others contemplated finding a way back home.

Trump on Monday declared a national emergency at the US-Mexico border and announced plans to send U.S. troops and restrict refugees and asylum, saying he wants to halt illegal entry and border crime. The measures follow a drop in illegal crossings in recent months. Supporters of the CBP One app that people like Castro used to try to enter legally say it brought order to a chaotic border. Critics say it was magnet for more people to come.

Adam Isacson, defense oversight analyst for the human rights organization Washington Office on Latin America, said Trump's crackdown on illegal immigration will surely deter migrants in the short term but will also have cascading humanitarian consequences. People with valid asylum claims may die in their own countries, he said, while migrants fleeing countries like Venezuela, Cuba and Haiti who cannot easily return home may end up floating around the Americas "completely unprotected."